Sputtering, alternatively called physical vapor deposition (PVD), has long been used depositing ionized metals from a target in the fabrication of semiconductor integrated circuits. Its use has been extended to depositing metal layers onto the sidewalls of high aspect-ratio holes such as vias or other vertical interconnect structures. Currently, advanced sputtering applications include depositing a metallic seed layer for later electroplating of the metallic layer in the via and depositing a barrier layer on the dielectric material of the via sidewall to prevent the metallic layer from diffusing into the dielectric.
Plasma sputtering may be accomplished using either DC sputtering or RF sputtering. Plasma sputtering typically includes a magnetron positioned at the back of the sputtering target to project a magnetic field into the processing space to increase the density of the plasma and enhance the sputtering rate. Typical magnetrons in some PVD chambers include magnets spinning about a central axis which spreads the plasma out over target surface to enable sputtering. However, these magnetrons don't offer any kind of control of the in the radial direction (i.e., from the center of the target to the edge of the target). Thus, in some areas, the plasma density may not be uniform across the sputtering surface of the target.
Accordingly, the inventors have provided embodiments of improved magnetron assemblies for use in substrate processing systems.